Trigger motor



Hum 29, 13943. G. W. PON-nus 3D., ETAL TRIGGEH MOTOR Filed Feb. 10, 1941 I VENTORS foe-W 2 @Juv 4 7 w 5 @WW1 Patented June 29, 1943 NITE!) LSTTS PATNT FFECE.

TREGGER MTGR George W. Pontius, lli, and George A. Goepfrich, South Bend, End.

Application February 10, 1941, Serial No. 378,148

(Cl. S9-27) 'l' Claims.

This invention relates to a trigger motor for guns, and more particularly to a trigger motor for automatic guns of the type wherein the breech bolt is held in a retracted position when the gun is not firing.

The invention will be described with reference to aircraft use, although it is not limited to guns for aircraft. The requirements for trigger' motors for aircraft guns are several. The firing unit as a whole must give an instantaneous response to the gunners iiring impulse since the sights of a gun are often on the target for a fraction of a second only. The firing unit must be light in weight and have a high poWer-to-weight ratio, as every ounce of weight is important in aircraft. Also the unit must be such that it can be detached readily from the gun, since guns must be removed frequently from the aircraft for cleaning and inspection, and it is desirable not to remove or disconnect any of the controls to the trigger motor.

In general, trigger motors for automatic guns of the type wherein the breech block is held in a retracted position must be more powerful than for the common type of gun wherein the cartridge is fired after the breech bolt closes on the firing chamber. of the gun, the trigger in effect being a breech block latch holding the breech bolt against the action of powerful return springs. The release of this latch requires much more'power than the release of a firing pin latch as is the case in other guns. Although an electric solenoid is satisfactory for an ordinary gun, a solenoid powerful enough to release a breech bolt would be prohibitively heavy and would require an excessively heavy current for the light aircraft batteries.

It is an object of the invention to provide a trigger motor giving rapid response to a firing impulse from the gunner.

It is also an object to provide a trigger motor having a high power-to-weight ratio.

A further object of the invention is to provide a readily detachable trigger motor.

Still another object is to provide a trigger motor of simple construction having a reliable and positive action, and which utilizes for its actuation hydraulic power derived from the operation of the engine.

Other objects and advantages of the invention will be apparent in the following description and claims which can best be understood when This is due to the construction considered in connection with the accompanying drawing, in which:

t Figure i is a diagrammatic plan view of an airplane carrying a 20 mm. cannon in each wing, and having trigger motors constructed according to our invention;

Figure 2 is a longitudinal sectional view oi the trigger motor;

Figure 3 is a view in section along line 3 3 of Figure 2; and

Figure 4 is a section along the line 4 4 of Figure 3 showing the detent for holding the trigger motor to the gun.

The invention is shown applied to an airplane lil (Figure l), which is driven by a propeller I2. A 2O mm. cannon i4 is mounted in each wing of the airplane just outside the arc of the propeller i2. The guns are of the automatic type, each having a breech block which is held in the retracted position when the guns are not firing. motor iS having a flexible hydraulic connection to to a solenoid operated valve il@ which selectively communicates connection I8 to a pressure line '42 for ring, or to an exhaust line 24 for ceasing re. The airplane iii has the usual hydraulic pressure system consisting of an exhaust reservoir 26 from which hydraulic fluid is passed to an engine-driven pump 28 which pumps it into an accumulator 3Q, which maintains the fluid under pressure in the known manner. The reservoir EE is connected to exhaust line 26 and the accumulator 30 is connected to pressure line 22.

The firing system is operated by energizing the solenoid valve 2d. This is done by means of a conductor 32 connected to each valve and energized by a firing switch 34 in the pilots or gunners cockpit, which switch is connected to a source of current such as battery 3S. When it is desired to ire the gun the pilot or gunner closes switch 3G, passing current to solenoid valve 2! which opens to pass high pressure uid to the trigger motor I6, causing the gun to lire. When it is desired to stop firing, switch Shi is released aliowing it to open, and this in turn de-energizes valve 2B, which acts to communicate conduit I8 to exhaust line Eil causing the gun to cease ring.

The solenoid valve 2G is of the pilot valve type wherein the solenoid operates a relatively small pilot valve, thus permitting control of a larg-e valve by a small, light-weight solenoid. rlhis valve is fully described in application Serial No. 371,742 led on behalf of Pontius and Wilson., December 26, 1940, and therefore will not be described here.

Each gun is equipped with a triggerv The trigger motor itself is shown in detail in Figures 2, 3 and 4. A base plate 40 is fastened by bolts 4| to gun |4 adjacent to a pivoted trigger latch 42 which holds the breech bolt 44 of gun I4 in a retracted position. The base plate carries a iitting 46 containing a spring 48 which urges a plunger 49 against trigger latch 42 insuring that it will always engage the breech block 44 upon recoil unless the trigger latch is held in the firing or non-engaging position as hereinafter described. Base plate 40 also retains a hardened steel insert 52 which acts as a buffer block when trigger latch 42 is moved to its firing position. Base plate 40 is formed with an integral collar 54 having a bore 56. Two parallel cylindrical grooves 58 are cut in collar 54 as shown in Figures 3 and 4.

A metal housing B has two intersecting passages 82 and 84 of unequal diameters. The housing 50 is provided with a collar 65, coaxial with passage 82, which rits closely over collar 54 on base plate 49. Housing 50 is held to base plate 40 by a detent 68 mounted in collar 85. As shown in Figure 4, detent 58 comprises a cylindrical part and a curved reduced part. By means of a push rod 69, detent 68 may be moved against the force of spring l until the reduced portion is in a position opposite collar 54, and housing 60 can then be placed on, or removed from, collar 54. When housing 80 is placed on collar 54 the spring l0 will force the cylindrical part of detent 68 into one or the other of the grooves 58, retaining the housing rigidly in position on collar 54.

A stepped piston l2, provided with any suitable packing 13, nts within the large bore 64 of housing 50. The central part of the piston is provided with a transverse rectangular aperture '|4 and is cut away in the region of the aperture to form a cam surface l5. A spring 18 is held against one end of piston i2 by a fitting 8i) screwed in one end of passage 54. The spring T8 acts as a return spring for piston i2 after the unit is subjected to hydraulic exhaust pressure, as hereinafter described. The hydraulic conduit I8 is fastened Ito the other end of passage 64.

The smaller bore E2 of housing G0 retains a cylindrical stem 82 which is provided with diagonal shoulders 85 adapted to coact with cam surface l in the operation of the device. From shoulders 85 inwardly, stern 82 is flatted on opposite sides as indicated at 8| and extends through aperture |4 of piston 12. Stem 82 carries at its inner end a T-shaped shank 84, the cross bar of which is set at 90 to the atted surfaces 8|. The T-shaped shank lits in a split tongue of the end of trigger latch 42. A hole 83 is drilled in the other end of stem 82 for a cable fastening in the event that manual iiring is desired instead of electro-hydraulic firing. A cover cap 88 closes the outer end of passage 62 and is screwed on housing 69.

If it is desired to remove gun I4 from the airplane l0, detent 58 is pushed inwardly, and when its reduced part lies opposite collar 54, the whole housing 68 can then be rotated 90 so that the cross bar of T-shank 84 is aligned with the split in the tongue of trigger latch 42. The housing 60 can then be pulled from base plate 40, and the two parts separated, T-shank 84 passing through hole 56 in base plate 40. The gun I4 may now be removed from the airplane I0 without the necessity of disconnecting the hydraulic lines. The units are assembled in the same way;

detent 68 is depressed; the housing 60 slipped on collar 54 at 90 to insert the T-shank 84 in trigger latch 42; and then housing 50 is rotated 90 until detent 68 snaps into one of the grooves 58 in collar '54.

In operation, the pilot fires the gun by closing switch 34 which causes solenoid valve 20 to open, passing high pressure liuid through flexible conduit |8 into housing 60. The fluid acts on piston 12 moving it against spring 18 and causing the cam surfaces 15, to move stein 82 outwardly from gun I4. A sufficient movement of stem 82 rotates trigger latch 42 releasing rbreech block 44 allowing its return to a liring position, whereupon the gun is red by automatic mechanism known in this art, and as a result recoils (to the right in Figure 2) until the breech block 44 again reaches the position shown in Figure 2. If stem E2 is still held outwardly, the breech bolt 44 will again be moved by the recoil mechanism (not shown) to the left, and the cycle will be repeated indefinitely.

If the pilot wishes to cease fire he opensI switch 34, causing valve 20 to communicate trigger motor I6 to exhaust. Spring 18 then forces piston T2 back to its starting point, relieving the pressure on stern 82. Stem 82 can then move inwardly toward the gun to release trigger latch 42. Spring 48 then forces trigger latch 42 into the path of reciprocating breech bolt 44, and upon the next recoil of the bolt 44, latch 42 will hold it in its retracted position, preventing further ring of the gun.

Although this invention has been described with reference to a particular embodiment thereof, it is not limited by the drawing or description or otherwise, except by the following claims.

We claim:

1. A hydraulic trigger motor comprising a housing with intersecting passages, a piston in one passage having a transverse rectangular hole therethrough and a relieved portion out on a diagonal in the region of the hole, a spring on the end of the piston opposite the diagonal cut of the relieved portion, a T-shaped stem fitting in said housing transversely to the piston, and passing through the hole in the piston and having a part engaging the diagonal cut of the piston, a collar on the housing adjacent to the T shaped stem, and a locking detent in said collar.

2. A trigger motor for a gun having a sear, comprising a hydraulic cylinder adapted to be connected to a source of hydraulic pressure, a piston in said cylinder having a cam surface associated therewith, a cam member extending through an aperture in the piston and cooperating with the cam surface, and an operative connection between the cam member and the sear to actuate the Sear.

3. A trigger motor for a gun having a sear, comprising a hydraulic cylinder adapted to be connected to a source of hydraulic pressure, a piston in said cylinder designed to be operated by said hydraulic pressure, yielding means for retracting said piston, a cam surface associated with said piston, a cam member extending through an aperture in said piston and cooperating with the cam surface to be operated thereby when the piston is operated, and connecting means between the cam member and` the sear to move the sear to inoperative position.

4. A trigger motor for a gun having a scar and a breech block, comprising an hydraulic cylinder adapted to be connected to a source of hydraulic pressure, a piston in said cylinder designed to be operated by said hydraulic pressure, yielding means for urging the piston to its starting position, a cam surface associated with said piston, a cam member cooperating with the cam surface of the piston and extending through an aperture in the piston, connecting means between the cam member and the sear to move the sear from engagement with the breech block, and yielding means to return the Sear to engagement with the breech block.

5. A trigger motor for a gun having a sear and a breech block, comprising an hydraulic cylinder adapted to be connected to a source of hydraulic pressure, a piston in said cylinder designed to be operated by said hydraulic pressure, yielding means for urging the piston to its starting position, a cam surface associated with said piston, a cam member cooperating with the cam surface of the piston and extending through an aperture in the piston, connecting means between the cam member and the sear to move the sear from engagement with the breech block, yielding means to return the sear to engagement with the breech block, a collar on the motor for enclosing the connecting means, and a detent in said collar for securing the motor to the gun.

6. In combination with a gun having a sear, a hydraulic trigger motor including a cylinder and a piston having a cam portion, a cylindrical extension on the cylinder, connecting means including a cam member extending through said extension and through an aperture in said piston for connecting the piston with the sear, a cylindrical extension on the gun in telescoping relation t0 the rst mentioned extension, and a detent associated with said extensions and operative in one position to prevent relative movement therebetween, said detent being manually movable to a position permitting separation of said extensions from each other.

'7. In combination with a gun having a sear and a breech block, an hydraulic trigger motor including a cylinder and a piston having a cam portion, a cylindrical extension on the cylinder, connecting means including a cam member extending through said extension and through an aperture in said piston for connecting the piston with the Sear, a cylindrical extension on the gun in telescoping relation to the first mentioned extension, and a detent associated with said extensions and operative in one position to prevent relative movement therebetween, said detent being manually movable to a, position permitting separation of said extensions from each other, and yielding means to return the sear to engagement with the breech block.

GEORGE W. PONTIUS, III. GEORGE A. GOEPFRICH. 

